A Three-Dimensional Integrated Circuit (3D IC) can be constructed using two or more layers of electronic components integrated into a single IC chip. These components may communicate using on-chip signaling, vertically and/or horizontally. A monolithic 3D IC may include electronic components and associated wiring built in layers on a single semiconductor wafer, which can then be diced into 3D ICs. A wafer-on-wafer 3D IC may include electronic components built on two or more semiconductor wafers, which can then be aligned, bonded, and diced into 3D ICs. Vertical connections can be built into the wafers before bonding and/or created in the stack after bonding. For example, Through-Silicon Vias (TSVs) can pass through silicon substrates between active layers and/or between an active layer and an external bond pad. A die-on-wafer 3D IC may include electronic components built on two semiconductor wafers. One wafer can be diced and the singulated dice can be aligned and bonded onto die sites of the second wafer. TSV creation can be performed before or after bonding. A die-on-die 3D IC may include electronic components built on multiple dice, which can then be aligned and bonded. TSV creation can be done before or after bonding.